Synthesis, structure determination, and formation of a theobromine : oxalic acid 2 : 1 cocrystal

The structure and the formation pathway of a new theobromine:oxalic acid (2:1) cocrystal are presented. The cocrystal was synthesised mechanochemically and its structure was solved based on the powder X-ray data. The mechanochemical synthesis of this model compound was studied in situ using synchrotron XRD. Based on the XRD data details of the formation mechanism were obtained. The formation can be described as a self-accelerated (‘liquid like’) process from a highly activated species.